Can language disorders inform of how language evolved? The human self-domestication answer

The view that language disorders are informative of previous stages in the evolution of language is controversial. In this paper, it will be argued that disorders can provide confident insights on how language evolved but only if discussed from an Eco-Evo-Devo perspective and within a general theory of language evolution. This claim will be illustrated by the consideration of the self-domestication account of human evolution and the evolutionary hypothesis for language that builds on it, and two prevalent cognitive disorders entailing language problems, namely, autism and schizophrenia. This approach linking ontogenetic damage to evolutionary novelty, and construing language evolution as the outcome of complex feedback loop effects between gradual changes in our body, cognition, behavior, and the environment is expected to also clarify the etiology and the symptomatology of human-specific disorders impacting on language.